Gov. Andrew Cuomo suggested Wednesday that he will not hold up his end of a much-touted bargain with the state teachers union to keep the use of student test scores from dragging down some teacher ratings.

In June, Cuomo agreed to protect English and math teachers in grades 3-8 from being negatively affected by Common Core-aligned test scores for two years. Only a small fraction of teachers would have qualified for the adjustments, but the governor said at the time he was concerned that any ratings based on the new tests might not be reliable enough to use to fire or deny tenure to teachers.

“People’s lives are being judged by this instrument,” Cuomo said in June, referring to the state tests, “so you want the instrument in the evaluation to be correct.”

But Cuomo never signed the “safety net” legislation, and districts have proceeded without making any changes. On Wednesday, as he criticized the low percentages of teachers who earned low ratings under the evaluation systems, Cuomo suggested publicly for the first time that he didn’t have any plans to sign that bill.

“I don’t know that those changes would make a significant difference to this data,” Cuomo said at a press conference in Albany.

The comments earned a swift rebuke from the New York State United Teachers, for which the deal was a victory after a years-long campaign to delay tying high-stakes for teachers to Common Core-aligned tests.

“This is the governor’s own bill,” NYSUT said in a statement. “He proposed it and it was negotiated in good faith.”

The safety net would have essentially offered a second chance to teachers who received an “ineffective” or “developing” rating on account of the state tests. It would replace the test-score component with other measures, such as observations, when the rating was used for personnel decisions like termination or creating improvement plans.

Cuomo’s comments came one day after the state education department released new teacher-evaluation data that showed far fewer teachers received the top “highly effective” rating in the city than did across the state. State education officials touted the city’s results as more accurate than the results from other districts, where — in some cases — much higher percentages of teachers earned the very highest or lowest rating.

But Cuomo made it clear that the city’s results still did not impress him.

He focused on the relatively few teachers who earned the lowest ratings in the 2013-14 school year, calling out New York City in particular, where 7 percent earned a “developing” rating and 1.2 percent earned an “ineffective” rating. (Just 2.4 percent of teachers in the rest of the state earned one of those low ratings.)

“It is incredible to believe that is an accurate reflection of the state of education in New York,” Cuomo said. “I think everybody knows it doesn’t reflect reality,” he added.

Cuomo did not say what he would consider a more realistic distribution of the four ratings, though he said his vision is to “reward the high performers and give the low performers the help they need.” His comments were the latest indication that he will mount an aggressive charge to change the teacher evaluation law for a fourth consecutive year, this time to make it more difficult for districts to ensure teachers earn top ratings.

The state only determines 20 percent of a teacher’s final rating, leading to a patchwork of plans across the state’s roughly 700 school districts. Cuomo said the current law gave a “disproportionate amount of power” to teachers unions, whose approval is required on all district plans.

In New York City, the union and the Bloomberg administration were unable to negotiate an evaluation system on time in 2013. King stepped in to settle the city-union disagreements, and the resulting plan, implemented a year later than the rest of the state, featured a system that prevented the scoring inflation that led to so many teachers with high ratings elsewhere.

Responding to Cuomo’s remarks, United Federation of Teachers President Michael Mulgrew defended the city’s system as one that other districts should learn from. Rather than overhauling the law again, Mulgrew said, districts should be given a chance to fix the problems themselves.

“I’m hoping the results from today will alleviate a lot of fears out there,” Mulgrew said Tuesday.

Mulgrew said more than 6,000 teachers rated ineffective or developing are currently following improvement plans, in which teachers and principals establish goals to improve weaknesses cited in their evaluations.

“If the idea of teacher evaluations was first and foremost to help people improve, we’re doing that,” Mulgrew said. Of Cuomo, he added, “How many more teachers on improvement plans would make him happy?”